Method of separating dice formed from a wafer



United States Patent Inventors John G. Willis Wakefield;

Johannes J. Van Den Broeke, Wilmington, Massachusetts Appl. No. 656,516

Filed July 27, 1967 Patented Nov. 3, 1970 Assignee 'lransitron Electronic Corporation Wakefield, Massachusetts a corporation of Delaware METHOD OF SEPARATING DICE FORMED FROM A WAFER l Claim, 3 Drawing Figs.

U.S.Cl 214/152, 9

214/1, 29/413, 29/426, 294/1, 294/87 Int. Cl B65g B2Sj J 3/00 Field of Search 29/426,

References Cited UNITED STATES PATENTS 317,234 5/1885 Spitzli 294/IX 5 l 7,295 3/l894 Pulling 271/33 3,272,350 9/1966 Pflaumer i 2l4/l52X 3,448,510 6/1969 Bippus et al. 29/413 Primary Examiner-Charlie T. Moon Attorney -W0lf, Greenfield and Sacks ABSTRACT: A mechanism and method for uniformly spreading apart a group of dice formed from a unitary semiconductive wafer after the dice have been severed from each other but before they are otherwise spread comprising a stretchable diaphragm secured at its periphery by an annular frame with the diaphragm adapted to be stretched over a surface having a circular edge and with the diaphragm adapted to be secured in its stretched position by engagement with the edge of a cylinder which fits over and is secured about the stretched diaphragm and surface.

METHOD OF SEPA'RATING DICE FORMED FROM A WAFER Y BACKGROUNDOF'THE i'NVENTlON This invention relates to a means and method of spreading apart a groupofspreadable objects comprising, for example, a plurality of dice immediatelyafter being formed from a single semiconductivc wafer.

in a variety of arts it isdesirable toprovide asirnple and effcient means for uniformly spreading a group .of components which are closely spaced .in their original position. There is a particular need for such a method and device in the semiconductor art where thousands of .minute pinhead-sized dice are simultaneously formed from u single wuferof semiconductlvc material. After formation of these multitude of dice they must be severed from each other and separately removed for subsequent insertion in individual semiconductor devices. While it is possible to separate these dice manually, or by other means, the methods practiced heretofore have .not been satisfactory for a variety of reasons. In order to maximize the efficiency of handling .these severeddice it is most desirable to physically spread them apart while still maintaining the rela tive orientation of the dice one to'the other. Manual separation and other means for effecting such acontrolled spreading or separation has not been satisfactory, and as a consequence present methods of separation are .quite expensive and time,

consuming. In addition it is desirable to minimize the physical handling by humans or machinery of .the dice since they are fragile and susceptible todamage in handling.

SUMMARY OF THE lNVE'NTlON it is therefore an object ofsthe present invention to provide an improved means andmethod of-spreading apart minute objects while still maintaining them in asclected orientationrela tive to each other. A further object of-tttis invention is to provide an efficient means and method of spreading'semiconductor components, especially dice. once they have been separated from a ser'nioonductive wafer, with little damage or loss of individual components.

A further object of the present invention is to=providea relatively inexpensive mechanism which is easy manufacture, maintain, repair and use for spreadingsmallcomponents.

In the present invention there is provideda mechanism for spreading apart a plurality of discreet objects comprising a resilient stretchable diaphragm designed to support the .objects. Means are provided .attheperiphery of the diaphragm to support it for stretching over a surface having a periphery smaller than the peripheryof the diaphragm andover which the diaphragm maybe stretched in a plurality of directions preferably including directions normal to one another whereby objectson thediaphragmymay be spread apart as the diaphragm is stretched,with the ,objects spreading uniformly in radial directions from a common center.

These and other objects and advantages of the present invention will be more clearly understood when considered in conjunctionwith thetaccompanying drawings.

BRIEF-DESCRIPTION OjF THEDRAWINGS lntbe drawings FIG. 1 is .a partially,cross sectioned elevational view of a device embodying 'thewmechanism .of the present invention, FIG.'2 is apartiallytcross-secti'oned topplan view of the embodiment illustrated in .FIG. 1, and FIG. Ms a somewhat schematicplan view of discreet components ofthe type which are to bc spread.

DESCRIPTION OF THE PREFERRED EMBODIMENT In the drawings there is illustrated'a preferred embodiment of a mechanism'designed to uniformly spread discreet ,components. Theparticular-embodiment [illustrated is specially designed for spreadingdicemut-from a common.semiconductive wafer. Ordinarily extremely thin semiconductor wafers having a diameter of l inchatoseveralinches in magnitude are scribed into hundreds to thousands of relatively small dice. in the order of magnitude of pinhead size. These dice are cut apart by conventional techniques. When the dice are separated they usually are scribed then broken or ordinarily remain in place relative to one another. lt is then necessary to separate or spread them so that the operator can individually pick them up and put them into the header ofa semiconductor device being formed or alternatively otherwise treat them.

In the drawings there is provided a diaphragm 1 of any suitable stretchable material such as rubber or synthetic material which is capable 'of stretching and then returning substantially to its original shape. This diaphragm is preferably secured by an annular band means 20 which in turn is preferably composed of an inner band 21 and an outer band 22. The diaphragm is secured in such a fashion that it is relatively planar and nonstretched or only slightly stretched when secured by the band means 20 and not under tension. The diameter of the band means is greater than the diameter of the platform 5 which has an upper surface 6 with a circular periphery 7. The platform 5 is suitably supported by a post 8 on a base 9 which may be rectangular or triangular in shape and which should have sufficient mass to adequately support the platform 5 and the other components herein described. A

plurality, preferably three, support posts 15 extend upwardly parallel to the post 8 withdistances spaced from the post such as to permit the annular band 20 to be moved downwardly between the three posts 15. These posts 15 extend upwardly preferably above the level of the surface of the platform 5. The posts 15 have a clamp mechanism 16 supported thereon and secured at a desiredposition by a setscrew 17.

The post is also provided with a tab 19 adapted to be rotated about the post with the tab secured against axial movement by a bushing and screw mechanism 25 and 26 which holds the tab against the clamp 16. The tabs 19 have lips or ends such as to permit them to engagethe flange 12 of thecylinder 10 after the flange has been pushed downwardly below the level of the tab.

The cylinder 12 isprefcrnbly formed ofn transparent plastic material and is provided with a cylindrical outer wall 28 having a removable cover 13 and an outwardly extending flange '12 about its periphery with the flange 12 intermediate its upper end 29 and lower .end 11. The flange 12 has sufficient width to permit engagement with tabs 19 when the tabs are rotated from an outwardlyextendngposition to one directed inwardlytowards the surface 6.

in the present invention after the semiconductor wafer is scribed by conventional means to define a plurality of dice in the then still integral wafer it is placed in this integral form scribed side down on a relatively soft surface, as for example a filter paper. The wafer then is rolledwith a small hard roller in a conventional fashion to break the wafer into a plurality of dice along the scribe lines. Following this the dice, after being broken apart, are picked up while still in their same relative nonsprcad position one to the other by the device shown in FIG. I. The dice are pickedup by turning the unit over so that the diaphragm l in its undistended or unstretched position is pressed against the obverse side of the dice which have been scribed and broken with their upper or treated surface face downwardly on the soft rubber surface. The diaphragm is then turned right side up with the dice clinging to the surface of diaphragm 1 so that their reverse surfaces or faces are visible. The diaphragm is then lowered downwardly over the surface 6 of the platform 5 whereby the diaphragm l is stretched uniformly in all radial directions from the center axis of the platform 5 thereby uniformly spreading the dice a distance which may be varied depending upon the desired degree of stretch, but is exemplified, for example, by the space 50. The diaphragm may be stretched by lowering the cylinder 10 downwardly so that its lower edges 11 uniformly engage the upper surface of the diaphragm outwardly of and equally distant from the periphery 7 of the surface 6. The cylinder 10 may be secured in adesired position by interengaging the clamp means 20 with the outwardly extending peripheral but are immediately'adjacent one another in their original relative wafer orientation comprising: transferringsaid separated dice in said original orientation to a stretchable diaphragm face down; stretching said diaphragm in a plurality of directions whereby said dice are moved apart; and thereafter removing said dice from said diaphragm simultaneously after separation by pressing a wet plate against said dice with said face remote from said plate, 

